Many modern operating systems executing on a computer provide a virtual area, often called a “desktop,” that serves as a user interface into which visual content such as images, icons, menus, or application user interfaces, may be drawn. The desktop, including its drawn visual content, may then be displayed onto one or more display devices connected to the computer. When the computer is connected to a single display device, the entire available desktop area is typically displayed on the display device. When multiple display devices are simultaneously connected to the computer, several modes of displaying the desktop are typically available, thereby providing additional benefits to the user.
In one such mode, often called “clone” mode, as illustrated by FIG. 1A, all connected display devices may display identical content, each displaying the entire available desktop area. In the example of FIG. 1A, the entire computer desktop 102—and thus the identical visual content—is displayed on both display device 104 and display device 106. This “clone” mode may be useful, for example, when the computer is connected to a computer monitor screen as well as to an LCD projector that is used to display a presentation.
Another desktop configuration mode for multiple simultaneously connected display devices, often known as “extended desktop” mode, is illustrated by FIG. 1B. In extended desktop mode, the size of the available desktop area is increased to account for the increase in display area due to the multiple display devices. FIG. 1B illustrates an example in which the two display devices 104 and 106 are of the same size. In the example of FIG. 1B, computer desktop 102 has been configured to be in extended desktop mode, and therefore has been extended to be twice the size. A first half 102a of computer desktop 102 is being displayed on display device 104, while a second half 102b of computer desktop 102 is being displayed on display device 106. Extended desktop mode therefore provides a user with a greater visual area for displaying such content as icons, menus and application user interfaces.
A typical computer desktop may be of limited use, however, to visually impaired users, who may not be able to adequately perceive content as it is typically displayed onto a display device. Accordingly, some users use Accessibility Technology (AT) software applications, such as ZoomText™ 9.1 Magnifier/Reader, developed by Ai Squared, Inc., of Manchester Center, Vt., that facilitates visually impaired users' use of computers. For example, such AT applications can apply enhancements, such as color enhancements, highlighting, magnification, or other enhancements, to a computer desktop to help a visually impaired user to more easily perceive displayed content. In one mode of operation, as illustrated by FIGS. 2A and 2B, an AT software application may magnify a portion (also referred to as a “viewport”) of a computer desktop 202. The viewport 206, rather than the full desktop area of desktop 202, is then displayed on a display device 204. In the example of FIG. 2A, although the viewport 206 is only a portion of the full area of desktop 202, it occupies the full display area of display device 204, thereby allowing for magnification of the content in the viewport.
The boundaries defining the viewport may be adjusted, thereby allowing a user to move a viewport to magnify or otherwise enhance a different portion of the desktop. As can be seen by FIG. 2B, viewport 206 has been moved to a different portion of desktop 202. The viewport may be moved, for example, when a user causes the mouse cursor to move to the edge of the current viewport boundary, which is taken as an indication that the user desires the viewport to be moved to display visual content beyond that edge boundary. Accordingly, display device 204 shows a magnified view of the different portion of desktop 202, rather than the portion defined by the position of viewport 206 in FIG. 2A.
Some AT software, including ZoomText™ 9.1 Magnifier/Reader, includes support for multiple display devices connected to the computer. When configured to use multiple display devices simultaneously, such AT software can operate in a variety of modes. FIG. 3 illustrates a first mode of operation, sometimes called “clone” mode. In the example of FIG. 3, rather than display the full desktop area of desktop 302 on display devices 304 and 306, the same viewport 308 (magnified appropriately) is displayed on both display devices 304 and 306. Thus, display devices 304 and 306 each displays the identical visual content. FIG. 4 illustrates a second mode of operation in which a magnified portion (i.e., viewport 408) of desktop 402 is displayed on display device 404, while the full desktop area of desktop 402 is displayed without magnification on display device 406.
FIGS. 5A and 5B illustrate a third mode of operation, sometimes called “span view” mode, for displaying a viewport onto multiple display devices. In “span view” mode, a different viewport of the desktop is created for each display device connected to the computer; however, the viewports have the same magnification level and are arranged contiguously on the desktop. In span view mode, the viewports remain contiguous even when the position on the desktop of one viewport is moved, thereby effectively providing a larger viewport area than would be available with only one viewport at an identical magnification level. Thus, in the example of FIG. 5A, viewports 508 and 510 have been created within computer desktop 502, and are displayed on display device 504 and 506, respectively. As can be seen from FIG. 5A, viewports 508 and 510 have an identical magnification level and are arranged contiguously, so that that they share a viewport boundary. Thus, desktop 502 can be considered conceptually as having a single viewport, divided into two halves, viewport 508 and 510. FIG. 5B illustrates a scenario in which the user has moved one of viewport 508 and 510 to a different portion of desktop 502. As can be seen by FIG. 5B, when one of viewport 508 and 510 is moved, the other viewport follows, thereby remaining contiguously linked to the viewport that moved.